Kinetics and Mechanism of the Reaction of Mercury(II) with a Water-soluble Octabromoporphyrin

Nahar, Nurun; Tabata, Masaaki

doi:10.1002/(sici)1099-1409(199807/10)2:4/5<397::aid-jpp100>3.0.co;2-w

Cited by 14 publications

(5 citation statements)

References 25 publications

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“…Interestingly, in sterically hindered coordinating solvents (2,6-lutidine and 2,4,6-collidine), the spectral features (Table 1) were not significantly different from those observed in non-coordinating solvents. The analysis of the plot of the ʻBʼ energy versus the solvent empirical E T (30) parameter fails to show any significant differences in correlation for Cu(II) perhaloporphyrins with that of CuTPP complex. Apart from the red-shift of the electronic absorption bands of Cu(II) perhaloporphyrins in coordinating solvents, the relative intensity of the Q bands (ε Q(0,0) / ε Q(1,0) ) showed an interesting solvent dependence.…”

Section: Cu(ii) Perhaloporphyrinsmentioning

confidence: 83%

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Sankar

Arunkumar

Bhyrappa

2004

J. Porphyrins Phthalocyanines

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Electronic absorption spectra of divalent metal (Ni(II) and Cu(II)) complexes of 2, 3,7,8,12,13,17,10,15, X = Br, Cl) were examined in various solvents. M(II) perhaloporphyrins exhibited dramatic shifts in their optical absorption spectral features relative to the corresponding metallotetraphenylporphyrins, MTPPs. Copper(II) perhaloporphyrins show significant red-shifts of the absorption bands in coordinating solvents relative to that observed for nickel(II) perhaloporphyrins. The large redshift of the electronic absorption bands and the gain in intensity of the longest wavelength band (Q(0,0)), of Cu(II) perhaloporphyrins in certain coordinating solvents is comparable to that found in meso-tetraphenylporphinatozinc(II), ZnTPP. The solvent dependent spectral features of M(II) perhaloporphyrins are attributed to a coordinative interaction of the solvent with the core metal ion induced by the electron deficient porphyrin macrocycle.

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Section: Cu(ii) Perhaloporphyrinsmentioning

confidence: 83%

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Sankar

Arunkumar

Bhyrappa

2004

J. Porphyrins Phthalocyanines

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“…18 In most papers on mercury(II) [tetrakis-(4-sulfonatophenyl)porphyrin] complexes, a species displaying a Soret-band at about 435 nm was discussed, but its composition has not been unambiguously determined; metal-to-porphyrin ratios of 2:1 24,26,89,126,129-131 and 3:2 128 have been proposed. Nahar and Tabata 131 proved that the 2:1 complex, if at all, could exist only in the narrow pH range of 2.5-4.Trimercury(II)-bisporphyrinswerewellknownbeforehand, 35,36 especially in the case of tetraphenyl-porphyrins. 132 Adeyemo and Krishnamurthy spectrophotometrically investigated the equilibrium in aqueous solution and found a species that they first considered as Hg 2 P 4-.…”

Section: Resultsmentioning

confidence: 99%

“…In most papers on mercury(II) [tetrakis-(4-sulfonatophenyl)porphyrin] complexes, a species displaying a Soret-band at about 435 nm was discussed, but its composition has not been unambiguously determined; metal-to-porphyrin ratios of 2:1 ,,,,− and 3:2 have been proposed. Nahar and Tabata proved that the 2:1 complex, if at all, could exist only in the narrow pH range of 2.5−4. Trimercury(II)-bisporphyrins were well known beforehand, , especially in the case of tetraphenyl-porphyrins .…”

Section: Resultsmentioning

confidence: 99%

Equilibrium, Photophysical, Photochemical, and Quantum Chemical Examination of Anionic Mercury(II) Mono- and Bisporphyrins

2008

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Mercury(II) ion and 5,10,15,20-tetrakis(parasulfonato-phenyl)porphyrin anion can form 1:1, 2:2, and 3:2 (metal ion/porphyrin) out-of-plane (OOP) complexes, from which Hg2P2(8-) has not been identified until now. Identification of this species significantly promoted the confirmation of the composition and the precise elucidation of the equilibrium of Hg3P2(6-). Since the formation of each complex is too fast, their kinetic behavior was studied from the side of dissociation. The rate-determining step in dissociations, as well as in the formation of the 2:2 complex, that is, the dimerization of 1:1 complex, proved to be virtually first-order under these conditions, while the consecutive formations of HgP(4-) and Hg3P2(6-) are second-order reactions. The equilibria can be spectrophotometrically investigated because the Soret- as well as the Q-absorption bands of the free-base ligand are more and more red-shifted in the series of 1:1, 2:2, and 3:2 complexes, and the split of Q-bands disappears as the singlet-1 excited states become degenerate; in the case of bisporphyrins, the bands broaden, especially in the longer-wavelength region of the spectra. The quantum yield and the lifetime of S1-fluorescence from the macrocycle is decreased by the insertion of a mercury(II) ion due to distortion, and in bisporphyrins the luminescence totally ceases because their more complicated structure promotes other ways of energy dissipation. The lifetime of the triplet excited-state is also reduced by metalation. The transient absorption measured upon excitation of Hg3P2(6-) probably originates from Hg2P2(8-) formed by efficient photodissocation during the laser pulse. This photoinduced dissociation is characteristic to out-of-plane complexes, but in metallo-monoporphyrins it needs the energetically higher Soret-excitation; in bisporphyrins, it can take place during irradiation at the longer Q-wavelengths. Investigation of the intramolecular photoredox reactions has proved that for the increased efficiency of the indirect photoinduced LMCT, not the redox potential, but the position of the metal center is responsible. The two orders of magnitude higher photoredux quantum yield for the 3:2 complex, compared to that of the 2:2 species, can be explained by the repulsive effect of the inner mercury(II) ion pushing the other two farther out of the ligand cavity. In bisporphyrins the second excited states are photochemically more reactive than the first ones, while most of the photochemical processes of HgP(4-) originate from the first excited state. According to our quantum chemical calculations, the mercury(II) ion causes the expansion of the porphyrin-cavity; therefore its out-of-plane position is smaller than the value expected based on its ionic radius. In the hitherto unknown 2:2 dimer two 1:1 saucer-shaped monomers are kept together by secondary forces, mostly by pi-pi interaction, but their relative arrangement was not unequivocally determined by the two DFT functionals used. The arrangements with a symmetry axis or plane perpendicul...

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“…In particular, fluorimetric/colorimetric sensors have the advantage of allowing simple on-site real-time detection for specific metal ions. [10][11][12][13][14][15][16][17][18][19][20][21] A few fluorimetric-colorimetric sensors with dual signaling have been reported for mercury, but most of them are not selective and suffer from interference by other metal ions. Furthermore, chemosensors have been reported in ''homogenious system'' as solution state, which is not recyclable.…”

Section: Introductionmentioning

confidence: 99%

Recyclable fluorimetric and colorimetric mercury-specific sensor using porphyrin-functionalized Au@SiO2 core/shell nanoparticles

Cho

Lee

Jung

2010

Analyst

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A fluorimetric/colorimetric mercury sensor based on Au@SiO(2) core/shell nanoparticles has been developed and demonstrated. The porphyrin derivative (2) was attached to Au@SiO(2) core/shell nanoparticles by covalent bonds and showed a red color and strong fluorescent properties. In the absence of specific metal ions, the porphyrin-functionalized Au@SiO(2) nanoparticles (1) exhibited strong fluorescence emission and were red in color. The addition of Hg(2+) ion to 1 resulted in a color change from red to green within 10 s and a weak display of fluorescence. Conversely, no significant changes in fluorescence emission or color were observed in the parallel experiments with Li(+), Na(+), Ca(2+), Cu(2+), Cd(2+), Co(2+), Mn(2+), Cd(2+), Ag(+) and Pb(2+). Regarding the reversibility of 1, the fluorescence and color of 1 in the presence of Hg(2+) ion were found to be almost reversible when 1 was treated with EDTA solution. Furthermore, a study of the effect of pH on 1 with bound Hg(2+) ion indicated that the fluorescence intensity and color change of 1 was almost constant between pH 4 and 10. This sensor has excellent selectivity and sensitivity over other metal ions and has detection limits below the maximum contamination level of 1.2 ppb for Hg(2+) ion in drinking water, as defined by the U. S. Environmental Protection Agency (EPA). The results obtained not only allow a practical sensing application for the Hg(2+) ion but also serve as a guide for the design of fluorimetric/colorimetric sensors for other targets.

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Kinetics and Mechanism of the Reaction of Mercury(II) with a Water-soluble Octabromoporphyrin

Cited by 14 publications

References 25 publications

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Equilibrium, Photophysical, Photochemical, and Quantum Chemical Examination of Anionic Mercury(II) Mono- and Bisporphyrins

Recyclable fluorimetric and colorimetric mercury-specific sensor using porphyrin-functionalized Au@SiO2 core/shell nanoparticles

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